Last link



A. R. SUMMERS 7 LAST LINK Aug. 10, 1954 Filed March 1} 1952 FIG.4.

j INVENTOR.

ARTHUR R. SUMMERS ATTORNEY Patented Aug. 10, 1954 LAST LINK Arthur It. Summer's,- St. Louis, Mo., assignor of one-half to Eskel J. McDaniel Application Marat 1. 1952, Serial No. 274,427

This invention relates to lasts used in manufacturing shoes and, particularly, tothe resilient hinge which connects the pivoted last parts.

Where the last toe and heel parts are pivotally connected, the parts must be provided with resiliently extensible linkage structure which passes over center relative to the last pivot point as the parts are broken or collapsed from the expanded, operative position. The linkage is received in registering slots or recesses formed in the abutting edges of the toe and heel parts and all of such links or hinges with which I am familiar extend wholly on the upper side of the axial line between the hinge pivots, it being thought that such disposition facilitates collapsing. Moreover, since rather heavy links must be provided to insure adequate strength and resiliency, large recesses must be cut in the wooden last parts to accommodate these links with consequent weakening .of the parts. I have found that the resilient last links now in common use produce considerable breakage across the weakened toe part and along a line intersecting the link pivot pin.

According to the present invention, this difiiculty is largely alleviated by formation of the linkage structure of a pair of similar, metal links centrally reduced and slightly bowed and arranged face to face, but oppositely bowed. This arrangement provides the required resilient extensibility of the link structure, while insuring the balancing out of all reactive forces within the last parts so that the total resistance to pivoting of the last parts is exerted along a line between the centers of the pivot pins and across relatively thick and strong portions of the last wood. Relaxing or tensing of the bowed links does not cause a purely rectilinear movement of the ends of the link, but actually involves a slight flattening or humping of the bowed portion of the link with a corresponding slight rotation of the journal portions of the link. By bowing the links oppositely, the rotations of the journal portions are in opposite directions, and consequently cancel each other out thus, in effect, eliminating all torsional forces on the pivot pins. This elimination of all forces on the hinge pivot pins at an angle to this axial line has resulted in a considerably stronger hinge structure and substantial reduction in breakage.

In the accompanying drawings which illustrate the invention:

Fig. 1 is a vertical, longitudinal section through a last embodying the invention in its expanded, operative position.

4 Claims. (c1. 12-136) Fig.2 is a similar view but showing the last in collapsed position.

Fig. 3 is an enlarged view of the link structure disassembled.

Figs. 4: and 5 are cros's-sections taken on the corresponding section lines of Fig. 3.

The lastin'cludes, as usual, toe and heel parts, generally designated as l and 3 having, respectively, pivotally interfitting, cylindrical recess 9 and tongue ill. Thep posed faces H and 12 of the last parts are angularly related, as shown, to permit the collapsing action, as illustrated in Fig, 2.

The last parts are normally secured together in their hinging relationship by means of the novel, resiliently extensible hinge link structure. This structure consists of a pair of similar, metal strap links i3 and M disposed in juxtaposition, face to face, in abutting relationship and with circular, terminal portions, as at l5, provided with aligned pin bearing openings i6. Such openings are provided in both terminal portions of the links, as shown. Intermediate the apertured end or terminal portions are bowed portions I! which are oppositely disposed to form the symmetrical, operative assembly. These intermediate portions are reduced in width so that the total widths of the oppositely bowed portions in the structure are not substantially greater than the widths of the registering, terminal portions. Thus, the link structure is of minimum effective width so that hinge receiving recesses l8 and H9 in the last parts may be constructed as small as possible with consequent minimized weakening of the last parts.

The assembled link structure is secured to the last parts by means of pivot pins 29 and Bi seated in the pin bearings It of the hinge structure. The relatively thick portion of toe part 1. between pin 2t and point 22, which results from the reduced recess 58, made possible by the narrower link structure, results in a considerably stronger last. At the same time, the link is of adequate strength and resilience and, what is more important, applies forces through the pins to the last parts only in the direction of the line between the centers of the pin. This is because the opposite disposition of the bowed portions of the hinge links results in balancing out of lateral and twisting or turning force components, as represented by vector lines A and B in Fig. 1, which would, otherwise, be applied to the pins and across the weakest portion of the toe part. I have found, accordingly, that the novel linkage structure results in the last being stronger and more durable, both due to the increased thickness of wood permitted and the balancing of the torsional forces applied by the link to pivot pins and through them to the last parts.

Various features may be modified as will ocour to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. A resilient link structure comprising a pair of similar links having aligned, terminal pin bearings and each having an in termediate bowed portion providing longitudinal resiliency, the bowed portions of said links being symmetrical and oppositely disposed with respect to each other.

2. A resilient link structure for a two-part shoe last comprising similar links having registering pin bearings and each having a bowed intermediate portion, the intermediate portions of the links being oppositely bowed and symmetrical with respect to each other whereby axial stretching of the link structure may be effected without the application of non-axial force components to structure linked thereby.

3. A resilient link structure for a two-part shoe last comprising similar, bowed links of strap material disposed face to face with aligned, transverse pin bearing openings in their end portions and with their intermediate portions reduced in width and oppositely bowed whereby for a two-part last the link structure is longitudinally extensible, said bowed portions being arranged with their central portions disposed on respectively opposite sides of said bearing openings whereby minimum last clearance need be provided therefor.

4. In a last, pivoted toe and heel parts having registering recesses, link structure connecting said parts and located in said recesses, said structure comprising similar links disposed with abutting faces and having aligned, terminal pin bearings, and pivot pins mounted in said toe and heel parts and said pin bearings, said links each having a bowed, intermediate portion providing resilient extensibility, the axis of said link on a line between said pins being adapted to pass over center during breaking and expansion of the last the bowed portions of said links being symmetrical and oppositely disposed with respect to each other thereby balancing non-axial forces applied to said pins and the last parts.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 712,797 Holtzmann Nov. 4, 1902 1,019,096 Soss Mar. 5, 1912 2,094,118 Cross Sept. 28, 1937 2,165,006 Reinhart July 4, 1939 2,356,888 Ryan Aug. 29, 1944 2,412,008 Reinhart Dec. 3, 1946 

